Virus‐specific capping of tobacco mosaic virus RNA: methylation of GTP prior to formation of covalent complex p126‐m 7 GMP

• Published in: FEBS letters Vol. 455; no. 1-2; pp. 45 - 48
• Main Authors: Merits, Andres, Kettunen, Reetta, Mäkinen, Kristiina, Lampio, Anja, Auvinen, Petri, Kääriäinen, Leevi, Ahola, Tero
• Format: Journal Article
• Language: English
• Published: 16-07-1999
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/S0014-5793(99)00856-X

In capping cellular mRNAs, a covalent GMP‐enzyme intermediate leads to formation of G(5′)ppp(5′)N at the 5′ end of the RNA, which is modified by methylation catalyzed by guanine‐7‐methyltransferase. Here we show that isolated membranes from tobacco mosaic virus (TMV)‐infected plant or insect cells expressing TMV replicase protein p126, synthesized m
7
GTP using
S
‐adenosylmethionine (AdoMet) as the methyl donor, and catalyzed the formation of a covalent guanylate‐p126 complex in the presence of AdoMet. The methyl group from AdoMet was incorporated into p126, suggesting that the complex consisted of m
7
GMP‐p126. Thus, TMV and alphaviruses, despite their evolutionary distance, share the same virus‐specific capping mechanism.